2 grams
6 x 106 = 636
3 x 105 = 315
315 x (2) = about 630
Multiply the first equation with (-1)
you should get this
-6r + 3t = -6
6r + 8t = -16
start to eliminate
11t = -22
divide by 11
t = -2
substitute
6r - 3(-2) = 6
6r + 6 = 6
6r = 6 - 6
6r = 0
r=0
Type into your calculator (if you haven't already): log 54.
My result: was similar to yours.
Note, however, that we're supposed to round off these results to the nearest thousandths (not thousand).
Your 1.73239 would need to be rounded off to 1.732, with 2 being the nearest thousandths.