Question

The sum of two numbers is 40. The second number is 5 less than twice the first number. Let x represent the first

number and let y represent the second number. What is the value of the first number? Use the table to guess and
check.
15
20
25
30
Mark this and return
Numbers
x+y=40
Save and Exit
Next
y-2x-5
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Answer 1

The sum of two number is 40 would be :

x + y = 40

The second number is 5 less than twice the first number would be :

y = 2x - 5

We can find the value by solving this system of equations, we will isolate x in the first equation, then we replace it in the second equation :

x = 40 - y

y = 2(40 - y ) - 5

y = 80 - 2y -5

y + 2y = 75

3y = 75

y = 75/3 = 25

We then replace this value in one equation of find the other variable :

x + 25 = 40

x = 40 -25

x = 15

Therefore the value of the first number is 15 and the second number is 25.

hope this helps :) !!!