Let's solve each equation step by step:

340 + (530 - z) = 210 3
Simplify the left side first:
340 + (530 - z) = 340 + 530 - z = 870 - z
Now the equation becomes:
870 - z = 210 3
870 - z = 630
Subtract 870 from both sides to isolate z:
-z = -240
Multiply by -1 to solve for z:
z = 240

830 - (90 8 - 5 b) = 260
Simplify the inside of the parentheses first:
830 - (720 - 5b) = 260
830 - 720 + 5b = 260
Now combine like terms:
110 + 5b = 260
Subtract 110 from both sides:
5b = 150
Divide by 5 to solve for b:
b = 30

Therefore, the solutions to the two equations are z = 240 and b = 30.