2А
1. What is the first step in simplifying the expression (2-3x4+5)^2

To simplify any algebraic expression, the following are the basic rules and steps: Remove any grouping symbol such as brackets and parentheses by multiplying factors. Use the exponent rule to remove grouping if the terms are containing exponents. Combine the like terms by addition or subtraction.

answer: 60

step-by-step explanation:

1/2a + (2/3×30)   = 50

1/2a + 20 = 50

1/2a = 30

a = 60

0.02

step-by-step explanation:

time of 9 192 631 770 periods of the radiation corresponding to the transition between the 2 hyperfine levels of the ground state of the caesium 133 atom at 0 k (but other seconds are sometimes used in astronomy)