You bought 12 one-gallon bottles of apple and orange juice for a school dance. the apple juice was on sale for $1.00 per one-gallon bottle. the orange juice was $1.75 per one-gallon bottle. you spend $15.00. how many bottles of each type of juice did you buy?

For this case we first define variables:
 x: bottles of apple juice
 y: bottles of orange juice
 We write the system of equations:
 x + y = 12
 1x + 1.75y = 15
 Solving the system of equations we have:
 x = 8
 y = 4
 
 you did buy: 
 8 bottles of apple juice
 4 bottles of orange juice

It should be a or d i’m not sure