Im not sure what they are asking but i found out what it is i think. Only for 1&2. For 1 i did 6/x=15/20. Cross multiply. 6 times 20 = 120. 15 times x = 15x. 120 divided by 15 is x=8.
#2 you would cross multiply again. 4 over x. = 5 over 15. 4 times 15 = 60. 5 times x = 5x. 60 divided by 5 = 12. So x=12. Sorry im not well with explanation.
