Algebra Tutor: None Selected Time limit: 1 Day

A girl is currently 5 years older than her younger brother and 3 years younger than her older brother. Two years from the current time, the product of the ages of the brothers will be 12 times the age of the girl. What is the current age of the older brother?

Oct 3rd, 2015

Let YB = younger brother’s age

Let OB = older brother’s age

Let YB + 5 = OB – 3 = girl’s age

Equation 1

YB + 2 + (OB + 2)  = 12*(YB + 5 + 2)

YB+2+OB+2 = 12(YB+7)

12YB+84 = YB+OB+4

12YB-YB-4+84=OB

OB=11YB+80

Equation 2

YB + 5 = OB – 3

Substitute OB

YB+5=(11YB+80)-3

YB+5=11YB+77

11YB=YB+5

11YB-YB=5

10YB=5

YB = 5/10 or 0.5 year or 6 months

Sep 18th, 2015

Final ANSWER: (please ignore the first one. It was the wrong file)

Let YB = younger brother’s age

Let OB = older brother’s age

Let G = girl’s age

Let YB + 5 = OB – 3 = girl’s age

ð  OB=YB+8

(YB+2)*(OB+2)=12*(G+2)

YBOB+2OB+2YB+4=12G+24

YBOB+2OB+2YB+4=12*(YB+5)+24

YBOB+2OB+2YB+4 = 12YB+60+24

YBOB+2OB=10YB+80

YBOB+2(YB+8)=10YB+80

YBOB=8YB+64

OB = 8+64/YB

Substitute

YB + 5 = OB – 3

YB+5=(8+64/YB) – 3

YB+5=5 +64/YB

YB=64/YB

YB^2=64

Yb=SQUAREROOT OF 64

YB = younger brother’s age = 8

Girl’s age = 13

Older brother’s age = 16

Sep 18th, 2015

...
Oct 3rd, 2015
...
Oct 3rd, 2015
Dec 7th, 2016
check_circle