7/10 of 80 is 56
4/5 of 80 is 64
3/4 of 80 is 60
5/8 of 80 is 50
1/2 of 80 is 40
1/4 of 80 is 20
1/10 of 80 is 8
1/8 of 80 is 10
to work these out divide the number by the denominator (bottom number) and multiply by the numerator (top number)
Explanation
A function is defined as a relation between a set of inputs having one output each,in this case our independent variable is the number of days( d) and the dependent variable would be the number of pizzas
so
Step 1
let the function

therefore, to know the number of pizzas are in the stock after 5 days we need to evaluate the equation for d=3
so

so, after five day there willbe 28 pizzas in stock
I hope this helpsyou
If you are doing the area of a rectangle, then it will be lw. Area of a triangle: lw/2.