One hundred stamps

A hundred letter stamps cost a hundred crowns. Its costs are four levels - twenty tenths, one crown, two-crown and five-crown. How many are each type of stamp? How many does the problem have solutions?

Correct answer:

n = 66

Step-by-step explanation:

x1= 0.2*10 +1*85+2*4+5*1 = 100
x2= 0.2*15 +1*76+2*8+5*1 = 100
x3= 0.2*15 +1*79+2*4+5*2 = 100
x4= 0.2*20 +1*67+2*12+5*1 = 100
x5= 0.2*20 +1*70+2*8+5*2 = 100
x6= 0.2*20 +1*73+2*4+5*3 = 100
x7= 0.2*25 +1*58+2*16+5*1 = 100
x8= 0.2*25 +1*61+2*12+5*2 = 100
x9= 0.2*25 +1*64+2*8+5*3 = 100
x10= 0.2*25 +1*67+2*4+5*4 = 100
x11= 0.2*30 +1*49+2*20+5*1 = 100
x12= 0.2*30 +1*52+2*16+5*2 = 100
x13= 0.2*30 +1*55+2*12+5*3 = 100
x14= 0.2*30 +1*58+2*8+5*4 = 100
x15= 0.2*30 +1*61+2*4+5*5 = 100
x16= 0.2*35 +1*40+2*24+5*1 = 100
x17= 0.2*35 +1*43+2*20+5*2 = 100
x18= 0.2*35 +1*46+2*16+5*3 = 100
x19= 0.2*35 +1*49+2*12+5*4 = 100
x20= 0.2*35 +1*52+2*8+5*5 = 100
x21= 0.2*35 +1*55+2*4+5*6 = 100
x22= 0.2*40 +1*34+2*24+5*2 = 100
x23= 0.2*40 +1*37+2*20+5*3 = 100
x24= 0.2*40 +1*40+2*16+5*4 = 100
x25= 0.2*40 +1*43+2*12+5*5 = 100
x26= 0.2*40 +1*46+2*8+5*6 = 100
x27= 0.2*40 +1*49+2*4+5*7 = 100
x28= 0.2*45 +1*28+2*24+5*3 = 100
x29= 0.2*45 +1*31+2*20+5*4 = 100
x30= 0.2*45 +1*34+2*16+5*5 = 100
x31= 0.2*45 +1*37+2*12+5*6 = 100
x32= 0.2*45 +1*40+2*8+5*7 = 100
x33= 0.2*45 +1*43+2*4+5*8 = 100
x34= 0.2*50 +1*22+2*24+5*4 = 100
x35= 0.2*50 +1*25+2*20+5*5 = 100
x36= 0.2*50 +1*28+2*16+5*6 = 100
x37= 0.2*50 +1*31+2*12+5*7 = 100
x38= 0.2*50 +1*34+2*8+5*8 = 100
x39= 0.2*50 +1*37+2*4+5*9 = 100
x40= 0.2*55 +1*16+2*24+5*5 = 100
x41= 0.2*55 +1*19+2*20+5*6 = 100
x42= 0.2*55 +1*22+2*16+5*7 = 100
x43= 0.2*55 +1*25+2*12+5*8 = 100
x44= 0.2*55 +1*28+2*8+5*9 = 100
x45= 0.2*55 +1*31+2*4+5*10 = 100
x46= 0.2*60 +1*10+2*24+5*6 = 100
x47= 0.2*60 +1*13+2*20+5*7 = 100
x48= 0.2*60 +1*16+2*16+5*8 = 100
x49= 0.2*60 +1*19+2*12+5*9 = 100
x50= 0.2*60 +1*22+2*8+5*10 = 100
x51= 0.2*60 +1*25+2*4+5*11 = 100
x52= 0.2*65 +1*4+2*24+5*7 = 100
x53= 0.2*65 +1*7+2*20+5*8 = 100
x54= 0.2*65 +1*10+2*16+5*9 = 100
x55= 0.2*65 +1*13+2*12+5*10 = 100
x56= 0.2*65 +1*16+2*8+5*11 = 100
x57= 0.2*65 +1*19+2*4+5*12 = 100
x58= 0.2*70 +1*1+2*20+5*9 = 100
x59= 0.2*70 +1*4+2*16+5*10 = 100
x60= 0.2*70 +1*7+2*12+5*11 = 100
x61= 0.2*70 +1*10+2*8+5*12 = 100
x62= 0.2*70 +1*13+2*4+5*13 = 100
x63= 0.2*75 +1*1+2*12+5*12 = 100
x64= 0.2*75 +1*4+2*8+5*13 = 100
x65= 0.2*75 +1*7+2*4+5*14 = 100
x66= 0.2*80 +1*1+2*4+5*15 = 100