Jamal got a job working on a assembly line in a toy factory, on the 20th day of work, he assembled 137 toys, he noticed that since he started , every day he assembed 3 more toys then the day before , how many toys did jamal assemble all together during his first 20 days

Answer 1

easy ...

d = 3 and
term20 = 137
a+19d = 137
a + 57 = 137
a = 80

now take the sum of first 80 terms

Answer 2

2170 toys