If a1 = 10 and an = an-1 + 5 then find the value of a5

Given,a1 =10 and an=an -1+5

Here,

a2=a 2-1 +5

or,a2=10+5

or,a2=15

Now,

a3=a2-1+5

or,a3=15+5

or,a3=20

Then,

a4=a4-1+5

or,a4=20+5

or,a4=25

At last,

a5=a5-1+5

or,a5=25+5

or,a5=30

Therefore,a5=30

b.-4 units

all you   do is count how many times you move