-2a + b = 29

3a + b = 39

therefore , -5a = -10 , a = 2 & b= 33

f(5) = 5*a + b = 5*2 + 33 = 10 + 33 = 43 .

yup , that's correct .

3a + b = 39

therefore , -5a = -10 , a = 2 & b= 33

f(5) = 5*a + b = 5*2 + 33 = 10 + 33 = 43 .

yup , that's correct .