For 1), plug in your variables to get A = 1500(1 + (7/100*1.5)). Simplify, and you’ll get A = 1500*1.105, and finally your answer, $1,657.50.
For 2), add your interest and principal amount, then plug in your variables to get 676 = 520(1 + 5r). Distribute to get 676 = 520 + 2600r. Subtract 520 from 676 to get 156 = 2600r, then divide both sides by 2600 to get a rate of 0.06, or 6%.
For 3), add your interest and principal amount, then plug in your variables to get 1599 = 1300(1 + 5.75t). Distribute to get 1599 = 1300 + 7475t. Subtract 1300 from both sides to get 299 = 7475t, and then divide both sides by 7475 to get .04 = t, or a time period of four years.
The other two problems can be solved using the formula and steps described above. If you still need help with them, leave a comment and I will solve those as well.