Q:

The students in Mr. Sanchez's class are converting distances measured in miles to kilometers. To estimate the number of kilometers, Abby takes the number of miles, doubles it, then subtracts 20% of the result. Renato first divides the number of miles by 5, then multiplies the result by 8.a) Write an algebraic expression for each methodb) Use your answer to part (a) to decide if the two methods give the same answer.

Accepted Solution

A:
Let 
x-----------> the distances measured in miles

 Abby method 
1)2x
2)2x-20%------> 2x-0.4x
algebraic expression-----> [2x-0.4x]---------> 1.6x

 Renato method 
1)x/5
2)(x/5)*8-------> 8x/5
algebraic expression----->[8x/5]---------------> 1.6x

Part B)
[2x-0.4x]=[8x/5]---------> 1.6x=8x/5--------> 5*(1.6x)=8x-------> 8x=8x
therefore
the two methods give the same answer
the answer is 1.6x