Can someone please explain step by step on how I get my answer on this question:
30% of 15?

3-12. write each answer with a reasonable number of figures. find the absolute uncertainty and percent relative uncertainty for each answer. (a) [12.41 (±0.09) + 4.16 (±0.01)] x 7.068 2 (±0.000 4) =? (b) [3.26 (±0.10) x 8.47 (±0.05)] - 0.18 (±0.06) =? (c) 6.843 (±0.008) x 104 + [2.09 (±0.04)- 1.63 (±0.01)] =?

Henry is an avid reader, he devours 90 pages in half an hour how many pages has henry read per minute?

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10