Sharron bought some Flibbertigibbets and some Whatchamajiggers. She bought 16 total items for a total of $42.
Flibbertigibbets cost $2 each, and Whatchamajiggers cost $4 each.
How many Flibbertigibbets did she buy? How many Watchamajiggers did she buy?

Create a system of equations where x is fibbertigibbets and y is whatchamajiggers.

x+y=16
2x+4y=42

Now solve the system

y=16-x
2x+4y=42

Use the substitution method:

2x+4(16-x)=42
2x+64-4x=42
-2x=-22
x=11

Plug this back into either equation to solve for y:

x+y=16
11+y=16
y=5

So x=11 and y=5, meaning there are 11 fibbertigibbets and 5 watchamajiggers.

Use a graph site then you will find your answer