Question

One number is 4 less than 3 times a second number. If 3 more than two times the first

number is decreased by 2 times the second number, the result is 11. Use the substitution
method. What is the first number?

Answer 1

The first number (x) = 8

Explanation:

Let x = the first number

Let y = the second number

x = 3*y - 4

2x + 3 - 2y = 11 Subtract 3 from both sides

2x - 2y = 11 - 3

2x - 2y = 8 Divide by 2

x - y = 4 Add y to both sides

x = y + 4 Now go back to the very first equation. Substitute for x

y + 4 = 3y - 4 Subtract y from both sides

4 = 3y - y - 4

4 = 2y - 4 Add 4 to both sides

4 + 4 = 2y

8 = 2y Divide by 2

8/2 = y

y = 4

x = 3y - 4

x = 3*4 - 4

x = 12 - 4

x = 8