(瓯海区)用递等式计算. ①104.8﹣5×10.4÷ ②2496÷48+1620 ③0.125×32×25 ④42×71.7+28.3×42 ⑤16.8﹣+3.2﹣.
20+30= 20+50= 20+60= 20+80=
10+20= 10+40= 10+50= 10+70= 20+20= 20+40= 20+50= 20+70=
30×1=____ 30×2=____ 30×3=____
20×1=____ 20×2=____ 20×3=____ 20×4=____
10×1=____ 10×2=____ 10×3=____ 10×4=____