you pay x for ten laps an you pay y for every additional lap you just multiply y by seven an add x
so all an all your answer would be (B)
Step-by-step explanation:

Y = Total
x = the amount of text messages sent
The equation is : y = 0.50x + 20
X | Y
1 | 20.50
5 | 22.50
10 | 25
(1,20.50)
(5,22.50)
(10,25)
If you add 35 + 15 that mean in all he shot 50 times so maybe if he does it again .. blah ion feel like explaining i think its D.55
7.1
X - 4.3 = 2.8
Add 4.3 to both sides
X = 7.1