Question

Find the two numbers where the sum is 85 and the difference is 15.

A. 40 and 45
B. 50 and 35
C. 30 and 55
D. 25 and 60

Answer 1

B

Explanation:

let the 2 numbers be x and y ( with x > y )

Form 2 simultaneous equations to solve for x and y , that is

x + y = 85 → (1)

x - y = 15 → (2)

adding (1) and (2) term by term will eliminate y

(x + x) + (y - y) = 85 + 15

2x + 0 = 100

2x = 100 ( divide both sides by 2 )

x = 50

substitute x = 50 into (1) and solve for y

50 + y = 85 ( subtract 50 from both sides )

y = 35

the two numbers are 50 and 35