7、? 50.4× 1.9- 1.8=95.76- 1.8=93.96 ? 3.76×0.25+25.8=0.94+25.8=26.74

8、54.5× 17=926.5? Do you want to get an integer? So 926 trees can be protected.

9,1.25+1.60+3.70× 4+2.40+6.60 = 26.65 (yuan) 30 & gt26.65? So buying is enough.

10, 0.25× 15=3.75 (km), 5×0.8=4 (km)? 4 & gt3.75 A: My home is 3.75km away from school, and it takes 0.8h to walk to school.