The 12th term of the arithmetic sequence is 10.5. The 18th term of this sequence is 13.5. Find the common difference and the first term

common difference is 0.5

first term is 5

Step-by-step explanation:

use the formula for the nth term of an ap Tn=a+(n-1)d

T12=10.5

T18=13.5

therefore come up with two equations

T12=a+(12-1)d

10.5=a+11d(1st equation)

T18=a+(18-1)d

13.5=a+17d(2nd equation)

then solve both as a simultaneous equation

a+11d=10.5

a+17d=13.5

-6d/-6=-3/-6

d=0.5

use one of the equations to find the first term

a+11(0.5)=10.5

a+5.5=10.5

a=10.5-5.5

a=5

I hope this helps

please mark as brainliest

i think it is 70

step-by-step explanation: