How do I solve this??

In a class, there are 12 girls. if the ratio of boys to girls is 5: 4 how many boys are there in the class

What is the total surface area of this square pyramid?

What is the volume of the cone to the nearest cubic millimeter? (use π  = 3.14) a) 46 mm3 b) 128 mm3 c) 183 mm3 d) 275 mm3 diameter = 5 mm height = 7 mm how do you do this problem step by step?