Question #4b52f

2 Answers
kubik98
Dec 22, 2017

41

Explanation:

Uncle must be older than Rohan because(suprise) Uncle is his uncle.
#U-R=30quad=>quadR=U-30#

#(R+7)+(U+7)=66#
#U=?#

#R+U+14=66#

#=>R+U=52#

#=>U-30+U=52#

#=>2U=82#

#=>U=41#

turksvids
Dec 22, 2017

The uncle is 41.

Explanation:

Let x = Rohan's age
Let y = Uncle's age
also I'm assuming the uncle is older...

Equation 1: #y-x=30#
(Think, if Uncle is 50 and Rohan is 20 this works.)

Next we know that in 7 years they'll both be 7 years older, so they'll be #x+7# and #y+7# years old at that point. At that point we know the sum of their ages, so:

Equation 2: #x+7 + y+7=66\rightarrow x+y+14=66#
So, #x+y=52#

Now we solve the system with equation 1 and equation 2:

#x+y=52# and #y-x=30#

Add the equations and we get #2y=82\rightarrow y=41#.

If #y=41# and #y-x=30# we know that #41-x=30#, so #x=11#.

Now we can check: If we add 7 to both we get 48 and 18, add those up and we get 66, so it works.

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