The halftime of radio active isotope is the time it takes for a quantity of the isotope to be reduced to half is initial mass starting with 160 g of a radioactive isotope how much will it be left after three half-lives

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)

The perimeter of a rectangle is 42 inches. if the width of the rectangle is 6 inches, what is the length

What is r i 4.5+10r=-6.5 with work pls