Help me please on hegarty maths

29.5cm^2

Step-by-step explanation:

3 × 4 = 12

4 × 2.5 = 10

3 × 2.5 = 7.5

12+10+7.5=29.5

5=812a+9+3

step 1: simplify both sides of the equation.

5=812a+9+3

5=(812a)+(9+3)(combine like terms)

5=812a+12

5=812a+12

step 2: flip the equation.

812a+12=5

step 3: subtract 12 from both sides.

812a+12−12=5−12

812a=−7

step 4: divide both sides by 812.

812a /812 = -7/812

a= -1/116

so the answer is

a=   -1/116

i believe the answer is c.