Q# 1 Solve each step with detailed answer: a) I have fifteen coins . Some are va

Question

Q# 1 Solve each step with detailed answer:
a) I have fifteen coins . Some are valued at 5 cents and others at20 cents. Their total value is $ 1.65 . How many 5-cents coins and20-cents coins do I have ? b) In five years time a father will three times as old as hisson.Four years ago , father was six times as old as his son. Findtheir Present ages? Q# 1 Solve each step with detailed answer:
a) I have fifteen coins . Some are valued at 5 cents and others at20 cents. Their total value is $ 1.65 . How many 5-cents coins and20-cents coins do I have ? b) In five years time a father will three times as old as hisson.Four years ago , father was six times as old as his son. Findtheir Present ages?

Explanation / Answer

a)Let x= number of 5cent coins and y= number of 20 centcoins. Then x+y=15 5x+20y=165 (165 cents) x+y=15 x+4y=33    Nowmultiply first equation by -1 and add the equations 3y=18 or y=6 and therefore x=9 b)Let S=age of son and F age of father F+5=3(S+5)     F-4=6(S-4) F-3S=10 F-6S=-20    Now multipy fifirst equation by -1and add -6S=-30 S=10     Substitute and you get F-3(10)=10or F=40 -6s=9

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