Question

5×(7×r-5)=225 срочно помогите решить !!!

Answer 1

$5×(7×r-5)=225 \\ (7×r-5)=225 \div 5 \\ 7×r-5=45 \\ 7×r = 45 + 5 \\ 7×r = 50 \\ r = \frac{50}{7} \\ r = 7 \frac{1}{7}$