Question 452378
The sum of a student's three scores is 228.
a + b + c = 228
;
 If the first is 21 points more than the second, 
a = b + 21
or
a - b = 21; will use this for elimination
:
the sum of the first two is 3 more than twice the third,
a + b = 2c + 3
:
what was the first score?
:
In the 1st equation, replace a+b with (2c+3), find c
2c + 3 + c = 228
3c = 228 - 3
c = {{{225/3}}}
c = 75 is the 3rd score
:
Replace c with 75 in the 1st equation 
a + b + 75 = 228
a + b = 228 - 75
:
a + b = 153
a - b = 21; addition eliminates b find a
-------------
2a = 174
a = {{{174/2}}}
a = 87 is the 1st score