Final answer:
To evaluate 0.5(a + b) - c with the given values of a, b, and c, we add a and b, multiply by 0.5, and then subtract c. The final simplified result is -23/20 or -1.15.
Step-by-step explanation:
To evaluate the expression 0.5(a + b) - c given that a=9/10, b=2/5, and c=1.8, we first need to add the values of a and b and then multiply the result by 0.5. Afterward, we subtract the value of c from the result to get the final answer.
• First, add a (9/10) and b (2/5).
• Convert 2/5 to tenths to get 4/10.
• Add 9/10 and 4/10 to get 13/10.
• Multiply 13/10 by 0.5 to get 13/20.
• Subtract c (1.8) from 13/20.
• Since 1.8 is the same as 18/10 or 36/20, subtract it from 13/20 to get -23/20.
The final answer in simplest form is -23/20 or -1.15.