If $x+3=10$, what is the value of $5 x+15$ ?

![](https://cdn.mathpix.com/cropped/2024_04_20_6027bc27089ed4fc493cg-035.jpg?height=406&width=380&top_left_y=957&top_left_x=1298)
(A) 110
(B) 35
(C) 80
(D) 27
(E) 50
Solution 1

ANSwER: (B)

Since $x+3=10$, then $x=10-3=7$.

When $x=7$, the value of $5 x+15$ is $5(7)+15=35+15=50$.

## Solution 2

When multiplying $x+3$ by 5 , we get $5 \times(x+3)=5 \times x+5 \times 3=5 x+15$.

Since $x+3=10$, then $5 \times(x+3)=5 \times 10=50$.

Therefore, $5 \times(x+3)=5 x+15=50$.

ANSWER: (E)