Hi there! I'm really confused and need help!

Question

I understand the material just fine. It's just this one problem that ticks me off!:

 

 

Half a pepperoni pizza plus three fourths of a ham-and-pineapple pizza contains 765 calories. One fourth of a pepperoni pizza plus a whole ham-and-pineapple pizza contains 745 calories. How many calories are in a whole ham-and- pineapple pizza? How many calories are in a whole pepperoni pizza?

 

I must solve this Linear System by the process of elimination. Thank You!

Answer 1

Let # of calories in a pepperoni pizza be p

     # of calories in a ham and pineapple pizza be h

 

1/2p + 3/4h = 765    (1)

1/4p +      h = 745    (2)

 

multiply (2) by 2;

1/2p + 2h = 1490    (3)

 

(3) - (1) ;1.25h = 725

 

therefore h = 725/1.25 = 580 calories

 

hence from (2) 1/4*p + 580= 745

 

1/4*p  = 745 - 580;  = 165; therefore p = 4*165 = 660

 

therefore number of calories in one pepperoni pizza= 660