Write 13/21 as decimal rounded to the nearest hundred

What other information do you need to prove triangle dac=bca by asa

The brain volumes (cm cubed) of 50 brains vary from a low of 904 cm cubed to a high of 1488 cm cubed. use the range rule of thumb to estimate the standard deviation s and compare the result to the exact standard deviation of 175.5 cm cubed, assuming the estimate is accurate if it is within 15 cm cubed

What is the answer to this question? i'm a bit stumped. also how do i do it? 5(x - 4) = 2(x + 5)