The graph shows the distance, y, in miles, of a moving motorboat from an island for a certain amount of time, x, in hours: What is the speed of the motorboat?
Group of answer choices
A. 35 miles per hour
B. 70 miles per hour
C. 105 miles per hour
D. 315 miles per hour

 The speed of the motorboat is 70 miles per hour

Step-by-step explanation:  Subtract the initial distance, 35, from the distance at any given time, then divide the remainder by the hours.

For example, at 2 hours, the distance shown on the graph is 175 miles

Subtract: 175 -35 = 140.  Then divide 140/2 = 70

At 4 hours, the distance shown is 315 miles.

Subtract: 315 - 35 = 280. Then divide  280/4 = 70

70 mph is the speed.

starting with:    

5 + x - 12 = 2x - 7   

5 + x - 12 - x = 2x - 7 - x (subtract x from both sides)   

5 - 12 = x - 7 (combine and cancel x's from both sides)   

5 - 12 + 7 = x - 7 + 7 (add 7 to both sides)   

0 = x (add numbers together on both sides)       

so in order for the equation to be true, x must be 0.   

trying x = -0.5   

5 + x - 12 = 2x - 7 (original equation)   

5 + -0.5 - 12 = 2(-0.5) - 7 (plug in value of x)   

5 + -0.5 - 12 = -1 - 7 (did multiplication)   

-7.5 = -8 (did addition on both sides)       

since -7.5 is obviously not equal to -8, the value of -0.5 for x is wrong.   

trying x = 0   

5 + x - 12 = 2x - 7 (original equation)   

5 + 0 - 12 = 2(0) - 7 (plug in value of x)   

5 + 0 - 12 = 0 - 7 (did multiplication)   

-7 = -7 (did addition on both sides)       

since -7 equals -7, that demonstrates that the value of 0 for x is correct.   

trying x = 1   

5 + x - 12 = 2x - 7 (original equation)   

5 + 1 - 12 = 2(1) - 7 (plug in value of x)   

5 + 1 - 12 = 2 - 7 (did multiplication)   

-6 = -5 (did addition on both sides)       

since -6 is obviously not equal to -5, the value of 1 for x is wrong.