I must have totally missed an entire module of this, leaving me rather dumfounded!!

Help!

1.) Y = 5x - 4 (X)

2.) E = mgh + ½mv² (H)

3.) E = mgh + ½mv² (V)

4.) E = mgh + ½mv² (M)

Apparently the letters in the brackets are the ones to "Isolate"

If anyone does help, could you please show me how to work them out for the future,

Thanks so much in advance,

D x