Emily manages a health bar and charges $2 for a banana smoothie and $2. 50 for a strawberry smoothie. She sold 40 in all and earned $87. How many banana smoothies and strawberry smoothies did she sell?
Solving System of Linear Equations by Substitution

What is the effect on the graph of the parent function f(x) = x when f(x) is replaced with 3f(x)? a) shifts the line 3 units up b) shifts the line 3 units down c) increases the slope of the line by a factor of 3 d) decreases the slope of the line by a factor of 3

Don't know how to find x given these segment lengths

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.