Question

If a + 3b = 13 and a + b = 5, the value of b is 1) 1 3) 4.5 2) 7 4) 4

Answer 1

a + 3b =13 ............... (1)

a + b = 5.............. (2)

By substitution from equation (1) a = 13 - 3b

Substituting for a in equation (2) yields

13-3b+b = 5

13-2b = 5

Bringing like terms together

13-5 = 2b

2b = 8

2b/2 = 8/2

b = 4

From Equation (2) a + b=5

a + 4 = 5

a = 5 -4

a = 1