Gabriel saved $3 in the first week and increased his savings by $4 each week. How much would he have saved at the end of 9 weeks?
Make a list: 3, 7, 11, 15, 19, 23, 27, 31, 35
Using rainbow method: 3 + 35 = 387 + 31 = 3811 + 27 = 3815 + 23 = 38Sum of each pair = 38Number of pairs: 4, left: 19 Sum of all pairs = [38 x 4] + 19 = 152 + 19 = $171 Answer(s): $171
