Question

m+c=20 2m + 4C=54 →Adicao​

Answer 1

$m + c = 20 \: \: \: \: \\ 2m + 4c = 54 \div 2 \\ m + 2c = 27 \: \: \: \: \: \: \\ \\ m + c = 20 \: \: \: \times ( - 1) \\ - m - c = - 20 \\ \\ - m - c = - 20 \\ m + 2c = 27 \\ 0m + c = 27 \\ c = 27 \: \: \: \: \: \: \\ \\ m + c = 20 \\ m + 27 = 20 \\ m = 20 - 27 \\ m = - 7 \: \: \: \: \: \: \: \: \:$

m=-7

c=27