Correct answers: 

1.3s + 1.7f = 37.9 ------ eq (i)

5.4s + 5.6f = 147.2____2(2.7s + 2.8f) = 2(73.6)_____2.7s + 2.8f = 73.6 ----- eq (ii)



In order to avoid too many decimals and very large numbers, you can do the following:

1.4s + 1.1f = 35.7 ----- Subtracting eq (i) from eq (ii) ------ eq (iii) 

.1s - .6f = - 2.2 ------ Subtracting eq (i) from eq (iii)------ eq (iv) 

s - 6f = - 22_____s = 6f - 22 ---- Multiplying eq (iv) by 10 ---- eq (v)

1.3(6f - 22) + 1.7f = 37.9 ------- Substituting 6f - 22 for s in eq (i) 

7.8f - 28.6 + 1.7f = 37.9

9.5f = 66.5





s = 6(7) - 22 ------ Substituting 7 for f in eq (v) 



You can do the check!! 

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