Final answer:
To evaluate the expression, substitute the given values into the expression and perform the operations to solve for the variable a. The solution to the equation is approximately a = 1.222.
Step-by-step explanation:
To evaluate the expression 0.25(a+b)-dta= 7/10 with the given values of b= 3/5 and d=-1/5, we substitute these values into the expression:
0.25(a + 3/5) - (-1/5)a = 7/10
Next, we simplify the expression by performing the operations:
0.25(a + 0.6) + 0.2a = 0.7
Combining like terms:
0.25a + 0.15 + 0.2a = 0.7
0.45a + 0.15 = 0.7
Subtracting 0.15 from both sides:
0.45a = 0.7 - 0.15
Simplifying:
0.45a = 0.55
Dividing both sides by 0.45:
a = 0.55/0.45
Calculating the decimal value to the nearest thousandths:
a ≈ 1.222