Question

Find two numbers which differ by 7 such that twice the greater added to five times the smaller makes 42

Answer 1

first of all two numbers are differ by 7
hence suppose greater number=x
&. smaller number =y
so
x-y=7. (1)
now twice the greater number i.e 2x is added to five times the smaller number. so,equation becomes,
2x+5y=42. (2)
by solving equation (1) & (2) we get
x=11 & y=4
so ans. is 11 & 4

Answer 2

Two equations and two unknowns.
Let two unknowns be x and y
Assume x to be larger
Eqn 1: x-y=7
Eqn 2: 2x+5y=42
Now put x=y+7 from Eqn 1 in Eqn 2 and get the answer.