Solve the equation (1) twenty fifth x = 1.2:75 (2) 1.5:4.5 = x: 60 (3) x + 60% x = 48 (4) (1-50%) x = 2.5

Solve the equation (1) twenty fifth x = 1.2:75 (2) 1.5:4.5 = x: 60 (3) x + 60% x = 48 (4) (1-50%) x = 2.5

(1)x/25＝1.2/75 75x＝1.2×25 x＝1.2×25÷75 x＝0.4
(2)1.5∶4.5＝x∶60 1∶3＝x∶60 3x＝60 x＝20
(3)x＋60%x＝48 1.6x＝48 x＝48÷1.6 x＝30
(4)(1－50%)x＝2.5 0.5x＝2.5 x＝2.5÷0.5 x＝5

123…… How much is 100

Is 1 + 2 + 3 always added to 100 equal to 1 + 2 + 3 100=（1+100）+（2+99）+（3+98）…… (49 + 52) + (50 + 51) there are 100 / 2 = 50 brackets in total, then the sum is 101 * 50 = 5050. According to this example, there are three summation formulas: ① (first item + last item) * number of items / 2 = sum ② (last item first item)

123 + 100 equals

323