Question

Mr. Rickman has two types of seeds. Blue grass seed cost $\$2.00$ per pound. While Green grass seed costs $\$3.00$ per pound. If for a particular day the two types of seeds cost total $\$68.00$ & together weighed 25 pounds. How many pounds of Blue grass seed did Mr. Rickman prepare ?

• A. 4
• B. 7
• C. 18
• D. 21

Answer 1

The correct option is B 7

Let, the number of pounds of Blue grass seed be b
and the number of pounds of Green grass seed be g
We know, they together weighed 25 pounds.
therefore, we have $b+g=25$
Also we know that blue grass seed costs $\$2.00$ per pound, therefore its cost will become $\$2b$
Similarly, for green grass seed, the cost will be $\$3g$
The expression for the total cost of the grass seed becomes $2b+3g$
$2b+3g=68$
Let's now solve these two equation
$b+g=25$
$2b+3g=68$

By using elimination method, we’ll begin by multiplying the second equation by 2

$2b+2g=50$
$2b+3g=68$
___________
$-g=-18$
$g=18$

Substitute $g=18$, in the second equation to solve for $b$
$b+g=25$
Subtract 18 from both sides, we get
$b=7$

Therefore, there are 7 pounds of blue grass seed.

Hence, option B is correct.