Answer: Ian's height = x+14 = 69+14 = 83 cm
Explanation :
Let the height of Jim be x
Let the height of Ian be x+4
Let the height of Lisa be x+4+10=x+14
Since their heights increase by 2cm every months
so after 7 months ,
Jim's height = x+14
Ian's height= x+4+14=x+18
Lisa's height= x+14+14=x+28
According to question,
Sum of Ian's and Jim's height = 170cm
⇒x =
⇒ x= 69cm
∴ Ian's height = x+14 = 69+14 = 83 cm