Which two signs need to be changed to make the following equation correct?
$$64 - 8 \div 3 + 7 \times 5 = 40$$

Given that 

$$64 - 8 \div 3 + 7 \times 5 = 40$$

we check option (A) $$\times and + $$

put the sign in the given expression 

$$64 - 8 \div 3 \times7 +5 = 40$$

LHS  $$ 64 - \dfrac {8}{3} \times 7 + 5 $$

$$\Rightarrow 64 - 2.66 \times 7 + 5$$

$$\Rightarrow 64 - 18.62 + 5$$

$$\Rightarrow 51.62 $$ its not staisfied RHS 

check option (B) $$\times and \div $$

we put Sign in the given option 

$$64 - 8 \times 3 + 7 \div 5 = 40$$

LHS $$64 - 8 \times 3 + 7 \div 5$$

$$\Rightarrow 64 - 24 + 1.4 $$

$$\Rightarrow 65.4-24$$

$$\Rightarrow 41.4$$ its not to RHS .

Again check option (C)$$\div and - $$

we put the Sign in the given expresseion

$$64 \div 8 - 3 + 7 \times 5 = 40$$

LHS $$64 \div 8 - 3 + 7 \times 5$$

$$\Rightarrow 8 - 3 +35 $$

$$\Rightarrow 43 -3 $$

$$\Rightarrow 40 $$ R HS it is staisfied   

then  option (C) $$\div and - $$ Ans