Answer:
The number is 27
Step-by-step explanation:
Let the 10s digit be x
Let the units digit be y
y = x + 5
10x + y = 3(x + y) Remove the brackets
10x + y = 3x + 3y Substitute the x + 5 into the second equation for y
10x + x + 5 = 3x + 3(x + 5) Remove the brackets on the right.
10x + x + 5 = 3x + 3x +15 Collect like terms on each side.
11x + 5 = 6x + 15 Subtract 5 from both sides
11x + 5 - 5 = 6x + 15 - 5 Collect like terms
11x = 6x + 10 Subtract 6x from both sides
11x - 6x = 6x - 6x + 10
5x = 10 Divide by 5
5x/5 = 10/5
x = 2
y = x + 5
y = 2 + 5
y = 7
