At the supermarket, each pound of soy beans costs 5 times as much as each pound of wheat. if the total cost of 4.7 pounds of soy beans and 2.4 pounds of wheat is $51.80, what is the cost of each pound of soy beans and each pound of wheat?

X=soy beans
y= wheat
x= 5y (because soy beans cost five times as much as wheat)

4.7x+2.4y= $51.80
Substitute x=5y
4.7(5y)+2.4y=51.80
23.5y+2.4y=51.80
25.9y=51.80
Divide both sides by 25.9
y=$2 cost of wheat per pound

x= 5y
=5(2)
=$10 cost of soy beans per pound

Check:
4.7x+2.4y= $51.80
4.7(10)+2.4(2)=51.80
47.0+4.80=51.80
51.80=51.80

Hope this helps! :)

Main idea on left, details on right