Find the measure of n in the following SEND HELP PLEASEEE

2.30+0.4-0.88+1.33 can u explain the answer to this why the answer is 3.15

Aline has a slope of 1/4 and passes through point (0.4,-1/2). what is the value of the y-intercept?

A) if $50000 is invested in a bank account that pays 9.3% of interest compounded on a six-monthly basis, how much money will be in the account after 3 and 12 years? b) if matusalen's father had put $2.0 in the bank when he was born and there, how long would matusalen have had to his death (969 years later) if the interest was 7% per year composed each month and weekly?