Question

Christin’s age is equal to three times her
age in 3 years’ time minus three times her
age 3 years ago.
How old is Christin?
A 10
B 12
C 15
D 18

Answer 1

Answer:

${\boxed{\bold{ANSWER:-D)18 }}}$

Step-by-step explanation:

Question:-

Christin's age is equal to three times her age in 3 years time minus Three times her age 3 years ago.How old is Christin?

A) 10

B) 12

C) 15

D) 18

$\rule{300}{1}$

Let present age of Christin be X years.

$\therefore\sf{After\:3\:years\:age=(X+3)\:years}$

$\therefore\sf{3\:years\:ago\:age\:was=(X-3)\:years}$

${\underline{\underline{\bold{According\:to\:question:-}}}}$

$\implies\sf X = 3(X+3) - 3(X-3) \\\\\implies\sf X =\cancel{ 3X }+ 9 -\cancel{ 3X }+ 9 \\\\\implies{\boxed{\sf {X = 18 }}}$

$\rule{300}{1}$

$\bold\purple {Verification:-}$

$\mapsto\sf 18 = 3(18+3) - 3(18 - 3) \\\\\mapsto\sf 18 = (3 \times 21) - (3 \times 15) \\\\\mapsto\sf 18 = 63 - 45 \\\\\mapsto\sf 18 = 18 \: \: \: \: \: [Verified!]$

$\therefore$ Christin is 18 years old.

Answer 2

Answer:

$\large\underline\textsf{christin Age was 18 year old }$

$\small \underline\textsf{ to find }$

$\sf{How \:old \:is \:Christin }$

$\huge\underline\textsf{Explantion:- }$

$\small\textsf{ Suppose the age of Christin be \red{Y years} }$

$\leadsto\bf after \: 3 \: year \: age = (Y+ 3)year$

$\leadsto\bf3 \: year \: ago \: age \: was = (Y - 3)year$

$\implies\bf Y = (Y + 3) - 3(y - 3)$

$\implies\bf Y = 3Y + 9 - 3Y + 9$

$\huge\implies\underline\textsf{Y = 18 year }$

$\rule{300}{2}$

$\huge\underline\textsf{Verification:- }$

$\implies\bf18 = 3(18+ 3) - 3(18 - 3) \\\implies\bf 18 = 3 \times 21 - 3 \times 15 \\ \implies\bf18 = 63 - 45 \\ \implies\bf18 = 18$

$\huge\underline\textsf{Hence verified }$

$\underline{\underline{\underline{\boxed{\boxed{\boxed{\bf{christin \:was \:18 \:year \:old }}}}}}}$