Answer:
y = 6.5
Step-by-step explanation:
Using a ratio
10 13
----- = -----------
10+5 13+y
10 13
----- = -----------
15 13+y
Using cross products
10(13+y) = 13*15
10(13+y) = 195
130+10y = 195
Subtract 130 from each side
10y = 65
Divide by 10
y = 65/10
y = 6.5
