Double-performance 17931

Excavation work was carried out by nine double-performance machines, which excavated 420 meters of excavation in one day. How many were there if the more powerful machine excavated 420 meters in a week (7 days) and the less powerful engine excavated 280 meters simultaneously?

Correct answer:

a =  3
b =  6

Step-by-step explanation:


a+b=9
420a + 280b = 420·7

a+b=9
420·a + 280·b = 420·7

a+b = 9
420a+280b = 2940

Pivot: Row 1 ↔ Row 2
420a+280b = 2940
a+b = 9

Row 2 - 1/420 · Row 1 → Row 2
420a+280b = 2940
0.33b = 2


b = 2/0.33333333 = 6
a = 2940-280b/420 = 2940-280 · 6/420 = 3

a = 3
b = 6

Our linear equations calculator calculates it.



Did you find an error or inaccuracy? Feel free to write us. Thank you!







Tips for related online calculators
Do you have a linear equation or system of equations and are looking for its solution? Or do you have a quadratic equation?
Do you want to convert time units like minutes to seconds?

You need to know the following knowledge to solve this word math problem:

Related math problems and questions: