Posted by Jacqueline on Monday, September 27, 2010 at 11:13pm.
Find the number of Calories in a grapefruit and an orange.
(1) An orange has 15 more Calories than a grapefruit.
(2) Twenty oranges and ten grapefruit have 1800 Calories.

8th grade math  PsyDAG, Tuesday, September 28, 2010 at 4:32pm
G = Grapefriut calories, R = oRange Calories
G = R  15
20R + 10G = 1800
Substitute R  15 for G and solve for R in second equation. Put that value in the first equation to find G. Check by putting both values in the second equation.