Question 994653
sams science marks is 15 less than his maths mark.the total of his two marks is 145.find sams marks for each subject. 
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Equations:
s = m-15
s+m = 145
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Substitute for "s" and solve for "m"::
m-15 + m = 145
2m = 160
m = 80 (his math mark)
s = 145-80 = 65 (his science mark)
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Cheers,
Stan H.
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