Question

3m + n = 71
2m - n = 30

Answer 1

m = 20.2; n = 10.4

Explanation:

`\left \bigg \{ { \big {3m + n = 71} \atop \big {2m - n = 30}} \right.; => \left \bigg \{ { \big {3m + n -3m= 71-3m} \atop \big {2m - n-2m = 30-2m}} \right.; => \left \bigg \{ { \big { n = 71-3m} \atop \big { - n = 30-2m}} \right. ; => \\\\=> \left \bigg \{ { \big { n = 71-3m} \atop \big { - n * (-1) = (30-2m)* (-1)}} \right.; =>\left \bigg \{ { \big { n = 71-3m} \atop \big { n = -30+2m}} \right..`

-30 + 2m = 71 - 3m

-30 + 2m + 30 = 71 - 3m + 30

2m = 101 - 3m

2m + 3m = 101 - 3m + 3m

5m = 101

5m ÷ 5 = 101 ÷ 5

m = 20.2

n = 71 - 3m = 71 - 3 × 20.2 = 10.4