15x + 6 - 7x - 8 can someone help me with this

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

What is the 12th term of b(n)=-4-2(n-1)

Acircle has a circumference of 28.36 units what is the diameter of the circle