Question 159538
Four hot dogs and a soft drink costs $6.30, whereas one hot dog and four soft drinks cost $4.20. What is the total cost of one hot dog and one soft drink?

Let h = hot dog

Let s = soft drink

4h + s = 6.30...Equation A

h + 4s = 4.20...Equation B


We have two equations in two unknowns.  The unknowns are the variables h and s.

I will solve for s in Equation A by subtracting 4h from both sides.

s = -4h + 6.30

I will now replace s in Equation B with -4h + 6.30 to find the price of one hot dog.

h + 4(-4h + 6.30) = 4.20

h -16h + 25.2 = 4.20

-15h = -25.2 + 4.20

-15h = -21

Divide both sides by -15.

h = -21/-15

h = 21/15

h = 7/5

h = $1.40

We now know the value of one hot dog.  

Go back to EITHER Equation A or B, replace h with 1.40, do the algebra and you will find the price of one soft drink.

I'll let you do that.

If you get stuck, write back.