If 450grams of flower is used for three pies how much is used for three pies?

450 grams you said 3 pies twice lol

If your asking how much each pie has its 450/3 = 150grams of flower for each pie. 

In this problem you would set these two equations equal to each other.
$8+ $1.50x = $10+ $1x 
After this you would simplify the equation to isolate x (being the number of toppings you put on the pizzas) 

$8+ 1.50x =$10+ 1x
-8              -8

$1.50x = $2 + $1x
-1x             -1x
 
$.50x/.50 = $2/.50

x= 4 toppings and the pizzas would equal $14 total