It is .21 or 21 cents for each pound.
You need to use a system of equations with 2 variables
where x= # of paintbrushes bought
and y= # of paint units bought
the first equation would be
.95x+.99y=4.87
Usually there is more information given in these problems so that you can make the second equation. Did the problem say how many total items were bought or anything else because given this information you cannot make a second equation and therefore cannot solve for both variables. Also, the wording is unclear, did she spend 4.87 on just paintbrushes or both brushes and paint.
4x + 89.95 = 628.35 <== ur equation
4x = 628.35 - 89.95
4x = 538.40
x = 538.40 / 4
x = 134.60 <== the cost for each cavity filling
It tells you.
(-2, 4)
(-1, 3)
(1, 6)
(3, 5)
(4, 8)
When x is 3, y is 5. The point (3, 5) tells us that.
True.
If the standard deviation value is larger, it means the data points are further away from the mean - which indicates that the data in the set are more variable.