To solve this we must set up a system of equations where x is the number of calories in a peice of cake, and y is the number of calories in a scoop of ice cream. when we do this, we get [tex]x=3y-20[/tex] and [tex]x+y=620[/tex]. So, to solve this sytem, you can use many methods, but I will use substitution. if we substitute the first equation for x in the second, we get [tex]3y-20+y=620[/tex]. solving for y, we get [tex]y=160[/tex]. then substituting this in to the first equation, we get [tex]x=460[/tex]. So the answer is there are 460 calories in a peice of cake and 160 calories in a scoop of ice cream.
