Question

Emmanuel bought 28 lb of potting soil this week. This amount is 4 lb more than twice the amount of potting soil he bought last week. Answer the following questions to find the number of pounds of soil Emmanuel purchased last week. (a) What is the unknown information?
(b)Let p represent the unknown information. Write an equation to model the problem.
(c)Which number, 10, 11, or 12, will solve the equation in Part (b)? Show your work.
(d)How many pounds of potting soil did Emmanuel buy last week?

Answer 1

Emmanuel bought 28 lbs of potting soil this week.  

Now this amount is 4 lbs more than twice the amount of potting soil he bought last week.  

So we need to find out how much potting soil did he buy last week.  

a. The unknown information in the problem stated above is the amount of potting soil Emmanuel bought last week.  

b. If 'p' represents the amount of potting soil he bought last week, then the equation to represent the situation can be given by:  

$2p+4=28$, since he bought 28 lbs amount is 4 lbs more than twice the amount (p) he bought last week.

c. Let p = 10 in the above equation.

So, $2(10)+4 = 24$ is not equal to 28.

Let p = 11 in the above equation.

So, $2(11)+4 = 26$ is not equal to 28.

Let p = 12 in the above equation.

So, $2(12)+4 = 28$ is equal to 28.

Therefore, the number '12' will solve the equation.

d. Emmanuel bought 12 pounds of potting soil.