If the backpack (b) contains only textbooks (t) and notebooks (n), the total weight of the backpack is:
b+t+n
but notebooks are 4 pounds, so actually:
b+t+4
also, the backpack weights 2 pounds, so the total weight is:
2+t+4 =t+6
now, "Seventy percent of
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the total weight is textbooks. ", this means that
t=70%(t+6) - this equation can be used to determine the weight of the textbooks!
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When you have ratios and some unknowns you can create complex fractions from them.Bring them to the same denominator and solve for X.
