代數question！

m=Mark 's present age
m-2= Mark 's two years ago age
5(m-2)=His father 's two years ago age
5(m-2) +2 = His father 's present age
so~
5(m-2) +2 = 5m-10+2 = 5m-8

式者我用中文解釋一次比你聽啦
Mark is m years old即係佢今年係m歲
咁Two years ago即係2年之前
佢阿爸就係佢5倍
條式即係(m-2)5=5m-10
但係條題目係問What is his father's present age?
即係問佢今年幾多歲
即係要+番2年
所以就係[(m-2)5]+2=5m-10+2=5m+8

Becase Mark was (m-2) years old two years ago.
Two years ago, father's age was 5(m-2) .
now, after two years, father's present age is 5(m-2) + 2
=5m-10+2 = 5m-8

Well you got confused at the year order...

Mark is m years old, then 2 years [ago] he is (m-2) years old, you're right here.

but be careful, Mark's dad is 5 time as old as Mark [2 years ago], not now...

Therefore his age is 5(m-2) years old...

To calculate the father's present age, just add 2 years to the above expression.

The overall statement is: 5(m-2)+2=5m-10+2=(5m-8)years old