PLS HELP ASAP WILL GIVE POINTS AND BRAINLIEST THANK YOU.

Solve the triangle. a = 21°, c = 105°, c = 5

Long division setup showing an incomplete calculation. 12 is in the divisor, 6839 is in the dividend, and 5 hundreds and 6 tens is written in the quotient. 6000 is subtracted from 6839 to give 839. an unknown value represented by a box is being subtracted from 839. what number should be placed in the box to complete the division calculation?

Use pascal's triangle to find the missing values. x4 - 4xb + 6x2 - ax + 1