Pls help! question is on the picture

Which linear equations have an infinite number of solutions? check all that apply.  (x  –  3/7)  =  2/7(3/2x  –  9/14)8(x  +  2)  =  5x  –  1412.3x  –  18  =  3(–6  +  4.1x)(6x  +  10)  =  7(x  –  2)4.2x  –  3.5  =  2.1 (5x  +  8)

What is the ratio of the length of an object in yards to the length of the same object in miles?

Idon't get undoing if its pass adding and subtracting so can someone ? x-2 over 5 = 18