Which names the opposite and absolute value of 12

How to use order of operation in 20 divide by 4 multiply 5 = 1

Afamily has five members. a mom, a dad, two sisters, & a brother. the family lines up single file. what is the probabillity that the mom is at the front of the line

Bob the builder is making 480kg of cement mix. this is made by cement, sand and gravel in the ratio 1: 3: 4