Step-by-step explanation:
arithmetic sequence : every new item of the sequence is created by adding a constant term to the previous item - in this case 195.
a1 = 3087 (that's our starting value)
a2 = a1 + 195
a3 = a2 + 195 = a1 + 2×195
an = a1 + (n-1)×195
a)
when he is 45 years old, that is 20 years (and 20 annual increments) plus to our starting value.
so, n = 1+20 = 21
a21 = a1 + 20×195 = 3087 + 20×195 = 6987
so, when he is 45 years old, his monthly salary will be RM6,987
b)
how many years (= how big is n) until he gets 8937 ?
8937 = a1 + (n-1)×195 = 3087 + (n-1)×195 =
= 3087 + n×195 - 195 = 2892 + n×195
6045 = n×195
n = 6045/195 = 31
so, a31 = 8937
and that means, he has to work 30 additional years (31 minus the starting level 1) to earn monthly RM8,937.
that means he will be 25+30 = 55 years old.
