# Certificate

There is 31 students in a class. From mathematics was'nt worse mark than 2. Average mark in mathematics was 2.

How many students have mark 1 and how many mark 2?

Result

n(1) =  0
n(2) =  31

#### Solution:

$(1\cdot a+2\cdot b)/31 = 2 \ \\ a+b=31 \ \\ \ \\ a+2b = 62 \ \\ a+b=31 \ \\ a = n(1) = 0$
$b = n(2) = 31$

(1*a+2*b)/31 = 2
a+b=31

a+2b = 62
a+b = 31

a = 0
b = 31

Calculated by our linear equations calculator.

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