Question 164651
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{{{x=Wilburs_Age}}}
{{{y=Freds_Age}}}
1st condition: {{{x+y=20yrs}}}, EQN 1
Also we get via EQN 1: {{{x=20-y}}}, EQN 2
2nd condition:
Wilbur's Age One year from now, so {{{x+1}}} ---> will be 9 times as Fred's age a year ago, {{{9(y-1)}}} right?
Putting into eqn the 2 ages via condition 2:
{{{x+1=9(y-1)}}}, EQN 3
Subst. EQN 2 in EQN 3:
{{{20-y+1=9y-9}}}
{{{21+9=9y+y}}}
{{{30=10y}}} -----> {{{cross(30)3/cross(10)=cross(10)y/cross(10)}}}
{{{y=3yrs}}}, Fred's Age now
Via EQN 2
{{{x=20-3=17yrs}}}, Wilbur's Age now
You can check by going to EQN 3, but it's nice going to condition 2 (it's the same anyway):
Wilbur's Age one year from now, 17+1=18yrs, will be 9 times as Fred's age a year ago, {{{3-1=highlight(2)}}}.See highlighted, is 9 times as Wilbur's age, (9*2=18yrs).
Thank you,
Jojo</pre>