Someone help please show work

Which is the standard form for this number? (4 x 1 100 ) + (8 x 1 1,000 ) + ( 3 x 1 100,000 ) ? a) 0.004803 b) 0.04803 c) 0.0483 d) 0.483

How many $20 bills do you need to have to make $280

The suare root of 9x plus 7 plus the square rot of 2x equall to 7