Solve for x

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In a box lenght 1m breadth 60 cm and height 40 cm small rectangular packets of dimension 5 cm into 8 cm into 10 cm are packed. how many such small packets can be packed in the big box?

Angles r and s are complementary. the measure of angle r is 31 degrees. which equation can be used to find angle s?

Aclassmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.