Chris was putting a railing on his deck. at the end of the day, he had 11.5 feet of railing left over. during the day, he had used two 1.5-foot-long piece of railing, one 3.25-foot-long piece of railing, and one 6-foot-long piece of railing.
how many feet of railing did chris have at the beginning of the day?
a.
start with 11.5. multiply 11.5 by 2. add 1.5 and 3.25 and 6.
b.
start with 11.5. multiply 1.5 by 2. add this product to 11.5. then add 3.25 and 6 to the answer.
c.
start with 11.5. add 1.5 and 3.25 and 6. multiply the answer by 2.

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.

the answer to your question is c.)   volcanoes built the mountains and earthquakes tore them down.

step-by-step explanation: